The best type of clothing is comfortable, loose fitting that allows you to move around easily. However, you want to avoid baggy tops especially with baggy arms as this will cause clearance issues with the bow string.
 
You must also avoid wearing open toed shoes because of stray arrows that may be embedded in the ground that have missed the target. This is in fact a GNAS ruling for competitions. Strong walking shoes/boots are the best type of foot wear to use.